update more copyright dates to 2020 for release

libcrypto breaks Mac (missing openssl/md5.h), so add option --enable-…

…libcrypto

tag version 5.1.0 release

tag version 5.0.0 final release

tag 5.0.0 alpha5

create tag for fourth 5.0.0 alpha release (introducing DSD)

create tag for third 5.0.0 alpha release

create tag for second 5.0.0 alpha release

create tag for 5.0.0 alpha release

create tag for 4.80.0 final release